Chapter IX. Influence Of Trees On Climate

Description

Chapter IX. Influence Of Trees On Climate

Forest Resources of India.—Formation and Development of the Forest Service of India.—Utility of Indian Forests, of What Consisting.—Traces of Flooded Areas.—Decrease of Stream in Punjab Rivers, to What Due.—The Temperature of Russia, How Affected by Forest Destruction.—Difficulty of Replanting Trees in Russia.—A Striking Illustration of a Forest-denuded Country.— Khanate of Bokhara.—Its Fertility Now and Thirty Years ago Contrasted. — Bavarian Observations. — Ascertained Influence of Forests on Climate, Relative Moisture, Fertility, and Healthful-ness, with Illustrations. — The Distribution of Rainfall and Forests of the United States.—Serious Discoveries in the United States in Connection with Forest Destruction.—An Unpleasant Future Prospect.—Industrious Prosperity of the United States, How Threatened. — Saying of Dr. Hayes and How it Concerns the United States.

A great deal has already been said in these chapters about the influence of trees on the climate of a country, but as some people seem to be sceptical on this subject we will add for their benefit a few more facts.

The formation and development of the forest service of India has been followed by a succession of reports that bring into prominence the great and varied forest resources of that country.

The work of classifying, demarcating, working, and managing was commenced and conducted so recently as the year 1863, and hence a thorough examination of the forests of India has not been completed. The expanse of country under the direct control of the government comprises every variety of climate, elevation, and temperature, and almost every form of soil and sub-soil.

The general forest administration has, therefore, to deal with the treatment of a great variety of forests, from the cool shade of the cedars that crown the middle ranges of the Himalayas, to the arid plains of the South, where the stunted vegetation scarcely yields a rafter for the peasant's hut, and thence to the tropical forests of Burmah, where the deep-green shade is never pierced by the sun's rays.

The utility of these forests consists of their supplies of timber-woods and other products for building, manufactures, food, or for the use and convenience of the people, while they indirectly affect the climate and soil, maintaining the supply of water in springs, streams, and even rivers. In certain parts there exist evidences that at some former period, where there was rice cultivation on a wide scale, there must have been large areas flooded with fresh water for a long succession of years, and that not by fitful floods of sudden inundation, but in a steady, quiet manner. At present there are to be seen only the dry beds of torrents, running as a torrent during the rainy season, and having a very small supply of water at other times. This phenomenon, as we are informed in Mr. Powell's report, so commonly observed in all the Punjab streams coming from the now denuded lower hills, points inevitably to the conclusion that forest denudation has deprived these rivers of their steady water supply, and hence ruined the rainless countries that were dependent on them.

The winters in Russia are becoming colder every year, and the summers hotter, more dry, and less fruitful, owing, as it is clearly proved by Palingston, to the destruction of the woodlands which formerly abounded in the southern districts. The clearing of these lands has caused such an evaporation that many once capacious watercourses have become mere swamps, or are completely dry. The Dnieper becomes every day more shallow, and its tributaries are no longer worthv the name of streams. The question of replanting has frequently been agitated, but the dried condition of the earth in many places in southern Russia makes it a matter of great difficulty.

A striking illustration of the results which have followed the denuding of a country of its forest trees, and a result which has been brought about within the short period of thirty years, is afforded by the Khanate of Bokhara, in Asia, a country situated between 35° and 45° north latitude, and 60° and 70° longitude east from London. Thirty years ago the Khanate was one of the most fertile provinces of central Asia, well wooded and watered, and was considered an earthly paradise. Twenty-five years ago a mania for forest-clearing broke out and continued until the timber had nearly all been destroyed. "What trees were spared by rulers and people were afterwards destroyed in course of a civil war. The consequence of this ruthless destruction of forest growth is now painfully manifest in immense dry and arid wastes, and the watercourses have become dry and useless channels. To ascertain by scientific observations the influence of forests on the annual rainfall, moisture of the air and ground, and on the climate generally, the Bavarian government established in different parts of the kingdom seven stations, at each of which daily observations were made at two different points, one situated in the middle of a large open field, the other in the middle of a large forest. These observations, according to Dr. Ebermeyer's report, agree with the observations and opinions given by Humboldt, De Saussure, Herschel, and other scientists in regard to the great influence of forests on the climate, relative moisture, fertihty, and healthfulness of a country, and are confirmed by the present physical condition of the Mediterranean shores, which, since the Alps, Apennines, and Pyrenees were deprived of their forests, have lost the verdure and fertihty so glowingly described by ancient geographers and historians. Rivers famous in story and song have sunk into insignificant streamlets, subject to sudden rises and overflows inundating and covering with gravel and sand the former fertile valleys. The destruction of the forests of the Vosges and Ceven-nes sensibly deteriorated the famous fertihty of Elasas and the rich valleys of the Ehone.

The same discoveries, although in a lesser degree, we are now making in various parts of the United States. The wholesale stripping of our republic's soil of its timber, continued at its present accelerated rates, a quarter of a century later will be followed by a long era of physical degeneracy and climatic deterioration that must sap its industrial and even its intellectual energies, and reduce its fair and salubrious bosom to the aspect of a South American llano.

Unless there can be excited a national interest in this subject, and preventive measures are set on foot, the vast interior of the United States must part with a great portion of its magnificent agricultural, manufacturing, and commercial prosperity.

I say that the distribution of rainfall in the United States is almost identical with the distribution of its forests. The eastern one third of the United States is a well-watered and well-wooded area. The prairie region east of the Missouri has a moderate amount of rain. The parallel of 60° is the northern limit of the forests. Dr. Hayes said he had often covered a whole forest, well grown, with his hat. This was in Greenland, but unless we protect our forests the same may some day be said of the United States.